The invention discloses a smelting method for LNG ship high-manganese steel. The smelting method comprises the following steps that (1) primary smelting is conducted through a primary smelting furnace, specifically, the adding amount of pig iron and molten iron is greater than or equal to 50 t and accounts for 50% or higher of the capacity of the primary smelting furnace, and tapped molten steel Pis lower than or equal to 0.004%; (2) LF furnace refining is conducted, specifically, metal manganese is added in batches for alloying, and the adding number of metal manganese is adjusted accordingto internal control components; (3) VD vacuum treatment is conducted, specifically, after VD treatment, all alloys are added according to target values, and the adding number of metal manganese is adjusted according to the internal control components; and (4) a continuous casting process is conducted, specifically, the molten steel superheat is controlled to be 45-50 DEG C for ladle handing casting, a steel blank is subjected to subsequent machining, and the LNG ship high-manganese steel is obtained. The manganese content in the steel is controlled to be 22.5-25.5%, the molten steel purity ishigh, as for the mechanical properties, Rp0.2 is greater than or equal to 400 MPa, Rm is 800 to 970MPa, A50 is greater than or equal to 22%, and low temperature impact toughness AKV at -196 DEG C is greater than or equal to 41 J.